In this study, we explored engineering doctoral students’ motivations for selecting their research topic. The extent to whichindividuals are intrinsically or extrinsically motivated and the autonomy they have to make their own decisions hasimplications for their enjoyment of and success at a particular task. Given the importance of motivation, we sought toaddress a gap in the understanding of how doctoral students in engineering decide on a particular problem to study. Ourfindings are based on interviews with students with varying past educational and professional experiences that enable us tocapture a wide range of motivations for engineering PhD students’ research subject decisions. We found that the majorityof students interviewed reported some form of extrinsic motivation guiding their decision, though these students varied intheir autonomy to select their own topic. Of the students who reported intrinsic motivations for their research topicselection, many had extensive prior work experience that informed their topic choice. Funding played a major role inshaping students’ project decisions, which is reflective of the scale and expense of much of engineering work. However, ourfindings suggest there are a number of opportunities for students to identify research topics in which they personallyperceive as important and interesting.